1. Field of the Invention
The present invention relates to refrigerators, and more particularly, to a defroster to remove the frost deposited on an evaporator, and a refrigerator employing the defroster.
2. Description of the Related Art
Generally, a refrigerating device comprises a compressor compressing a gaseous refrigerant at a high temperature and with a high pressure, a condenser to condense the compressed gaseous refrigerant into a liquified refrigerant, a capillary tube to convert the liquified refrigerant to be conditioned at low temperature and low pressure, and an evaporator to refrigerate the ambient air by absorbing latent heat around the evaporator to gasify the liquified refrigerant at low temperature and with low pressure from the capillary tube. The insides of a freezer chamber and a refrigerator chamber can be cooled by supplying the air cooled around the evaporator into the insides of both compartments.
This kind of refrigerating device can be used in a various manner, for example, in heat exchanging devices such as a refrigerator and an air conditioner, etc. Hereinafter, a refrigerating device employed in a refrigerator will be described by way of example.
A general refrigerator includes a main body partitioned into a freezer compartment and a refrigerator compartment, doors rotationally opening and closing front openings of the freezer compartment and the refrigerator compartment, and a refrigerating device cooling insides of both compartments.
Since the surface temperature of the evaporator provided in the refrigerating device of the refrigerator is lower than the temperature of the air within the refrigerator, moisture mixed with the air inside the refrigerator is deposited on the surface of the evaporator in the form of frost. This frost will cause the evaporator's ability for heat exchange to be deteriorated. Thus, defrosting devices, such as an electric heater, are required to remove the frost deposited on the evaporator.
As illustrated in FIGS. 1 and 2, a defroster employed in a conventional refrigerator comprises a defrosting heater 50 provided in a lower part of a cooler chamber 30 positioned in back of the freezer compartment 70 of the refrigerator and removing the frost deposited on a cooler 40 by generating heat when it is placed in a defrosting mode in response to an electric signal from a controller; a heat exchange part 4 formed by bending a defrosting tube 1 vertically several times and situated in back of the cooler 40 provided inside the cooler chamber 30; and a reflection plate 31 of an aluminum material, mounted in back of the heat exchange part 4 so as to prevent the heat radiated from the heat exchange part 4 from being transferred backward toward the cooler chamber 30.
The defrosting tube 1 is extended downward from the heat exchange part 4 and connected to a first side of a storing tank 2, being communicated with the inside of the storing tank 2, and is extended upward from a second side of the storing tank 2 and connected to the heat exchange part 4 via a pump 3. Here, the storing tank 2 is mounted on the top of the compressor 21 in a component chamber 20 and stores an antifreezing solution to defrost.
Further, in back of the freezer compartment 70, there are provided a rubber insulation 26, a cool air discharging outlet 37 formed above the rubber insulation 26, and a thermo-damper 35 provided adjacent to the cool air discharging outlet 37 and opening and closing the cool air discharging outlet 37 in response to the electric signal from the controller.
In the conventional refrigerator employing the above-described configuration, when the controller changes the mode of the refrigerator from a cooling mode into a defrosting mode in response to a signal from a frost sensor (not shown) or from a defrosting timer (not shown), an operation of the compressor 21 is suspended and a cooling system thereof is suspended accordingly. Then, the defrosting heater 50 starts to generate heat in response to an operation of the defrosting system, and the pump 3 and the thermo-damper 35 are operated.
Then, the antifreezing solution, such as ethylene glycol, propylene glycol, etc., stored inside the storing tank 2 is supplied by the pump 3 into the heat exchange part 4 within the cooler chamber 30 through the defrosting tube 1, and at the same time, a cool air discharging outlet 37 is closed by the thermo-damper 35 and a freezer fan 33 is rapidly rotated.
The antifreezing solution stored inside the storing tank 2 is heated up by the heat generated by an operation of the compressor 21 and conditioned at a high temperature of 90° C.˜100° C. in the cooling mode, and is discharged along the defrosting tube 1 if the mode of the refrigerator is changed into the defrosting mode according to a signal from the controller, to thereby cause the heat exchange part 4 to generate heat, and then discharged into the cooler 40 by a forced hot air generated by rotation of a freezer fan 33, to thereby cause the frost deposited on the cooler 40 to be removed.
As described above, defrosting has been performed with the heat generated by the defrosting heater 50 mounted on the bottom of the cooler in the conventional refrigerator. In addition, the defrosting is effectively performed within a short period of time by supplying the antifreezing solution, heated with the use of the heat from the compressor 21, into the heat exchange part 4 of the cooler chamber 30 and discharging the heat radiated from the heat exchange part 4 into the cooler 40 by the forced hot air generated by means of the freezer fan 33 in the state that the thermo-damper 35 closes the cool air discharging outlet 37 so as to prevent the forced hot air from being flowed toward the freezer compartment 70.
However, the defroster used in the conventional refrigerator is disadvantageous in that it separately needs a defrosting heater to remove the frost on the cooler, and also uses a pump to supply the heat from the compressor into the heat exchange tube assembly, thereby having a complicated structure and consuming extra power.
Further, conventional refrigerators have been designed to perform the defrosting operation in the range of 10 hours to 48 hours, which may vary depending on some conditions of the refrigerators, and thus, this causes the evaporator to be deteriorated in performance because of the frost deposited for a long time before a next defrosting operation commences after the previous defrosting completed.
Further, if the frost is partially deposited on the evaporator, a part of the evaporator, on which the frost is not deposited, is heated while the defrosting operation is performed, thereby increasing the inner temperature of the refrigerator.